The present invention relates to the field of cranes, and more particularly relates to a detecting and monitoring device for the hook angle of a crane. The present invention also relates to a crane with a detecting and monitoring device for the hook angle.
Cranes requirement vertical lifting, as stipulated in construction specifications of cranes. The hook angle should not exceed 3 degrees when using a mobile crane lifting a workpiece. However, so far there are no vertical lifting displays on cranes. As a consequence, crane drivers cannot determine whether the hooks are in the vertical position. Though the vertical information of a hanged workpiece may be provided by a hoisting commander who observes the workpiece constantly, such information is neither timely and accurate.
For many years, the detection of the hook angle of a crane is obtained by detecting the angle of the steel rope of the hook or through the machine vision technology to detect the verticality of the hook. In addition, another method that is mentioned in the patent with the application number CN2011103601730 is to directly detect the deviation of the action line of lifting force to the plumb line. During the process of lifting, the hook and the lifting pulley assembly of the crane have identical deviations, and there is a laser generator fixed on the lifting pulley assembly of the crane, the light spot in the reflecting surface of the reflector body transmitted by the laser generator, the position corresponding angle value indicate by the concentric circles, and dynamic display declination angle direction and the declination angle degrees of the hook. The patent with the application number CN2011103871994 mentions a measurement platform that is mounted on the outside of the fender of the movable pulley of the lifting pulley assembly of crane, where the measurement platform surface is horizontal when the vertical deviation angle is zero, a vertical coordinate system is set on the measurement platform surface, and a biaxial inclinometer is also set up to measure the vertical deviation angle of the X-axis and Y-axis.
There are many styles of lifting pulley assembly relating to the detection of the hook angle, and the parts of the lifting pulley assembly are not uniformly defined and named. The following are two typical existing pulley hook assembly. FIG. 1 is a schematic view of a lifting pulley assembly setting up two sides of the fender for lifting. In the FIG. 1, 1—fixed pulley, 2—moved pulley, 3—steel rope, 4—fender, 5—hook. FIG. 2 is an schematic view of a lifting pulley assembly with an additional board between the lifting pulley assembly and the hook: 1—moved pulley, 2—pulley shaft, 3—fender or shield of the fender, 4—hook, 8—a board added between the lifting pulley assembly and the hook, where the hook is fixed on the hook beam 6 by nut 5, and a bearing 7 is set between the nut and the hook beam 6.